First time right placement of a DBS lead

ABSTRACT

The disclosure is directed to a deep brain stimulation (DBS) lead having a distal end for providing therapeutic electrical stimulation to tissue in a stimulation target area of a patient&#39;s brain, comprising an array of one or more stimulation elements and sensing elements located at the distal end of the lead; each of the one or more stimulation elements is capable of providing electrical stimulation to the brain tissue in the target area; and each of the one or more sensing elements is capable of detecting electrical signals produced by nerve cells within the brain; wherein after the first implantation of the lead into the brain along a trajectory that is pre-determined by non-surgical procedures, the array of stimulation and sensing elements is capable of facilitating the location of the target area and the determination for each of the stimulation elements of the required stimulation parameters needed to provide the therapeutic stimulation to the brain tissue in the stimulation target area, without requiring any additional implantations of the lead after the first implantation. A stimulation system including the DBS lead and a pulse generator is disclosed. Also disclosed is a method of providing therapeutic DBS to brain tissue using the lead.

The disclosure is directed to a deep brain stimulation (DBS) lead havinga distal end for providing therapeutic electrical stimulation to tissuein a stimulation target area of a patient's brain, comprising an arrayof one or more stimulation elements and sensing elements located at thedistal end of the lead; each of the one or more stimulation elements iscapable of providing electrical stimulation to the brain tissue in thetarget area; and each of the one or more sensing elements is capable ofdetecting electrical signals produced by nerve cells within the brain;wherein after the first implantation of the lead into the brain along atrajectory that is pre-determined by non-surgical procedures, the arrayof stimulation and sensing elements is capable of facilitating thelocation of the target area and the determination for cach of thestimulation elements of the required stimulation parameters needed toprovide the therapeutic stimulation to the brain tissue in thestimulation target area, without requiring any additional implantationsof the lead after the first implantation. A stimulation system includingthe DBS lead and a pulse generator are disclosed. Also disclosed is amethod of providing therapeutic DBS to brain tissue using the lead.

Successful deep brain stimulation treatment requires an accurateplacement of the stimulation electrodes within the stimulation targetarea. In current best practice, prior to the implantation of the chronicstimulation electrodes a major amount of time during the surgicalprocedure is spent on the electrophysiological exploration withmicro-electrodes of the target area. This lengthy procedure extends thesurgery by hours and a solution that allows the same, or better,electrophysiological mapping of the target area for stimulation ishighly desired.

Following the first demonstrations of the disappearance of tremor uponelectrical stimulation of thalamic targets in the late 1980s, deep brainstimulation (DBS) has become an accepted technique for the treatment ofadvanced Parkinson's disease. A lead carrying a number of electrodes(typically 4 circumferential electrodes, for example, as in theMedtronic DBS electrode 3389) is surgically implanted in the stimulationtarget, for instance the subthalamic nucleus (STN) or the globuspallidus internal segment (GPi). This lead is connected by means ofextension wires to a pulse generator, which produces the electricalpulses required for the stimulation. The typical parameters for socalled high-frequency DBS (HF-DBS) are pulse length 60-100 μs, pulserepetition frequency 130-185 Hz, and pulse amplitude 1.5-5 V. It isgenerally accepted that under these conditions HF-DBS mimics the effectsof a functional lesion of the stimulation target.

An important merit of HF-DBS is its reversibility. When the electricalstimulation is interrupted its effects are fully undone. This is a clearadvantage over respective surgery, which is irreversible by nature, andit allows to cease, or adjust, the treatment in case of negativeoutcomes. Moreover, the spatially localized delivery of the electricalstimulation is an important advantage over pharmaceutical treatments,where typically the drugs exert a global effect often leading tounwanted side-effects. Asserted by both the clinically proven efficacyof the method for Parkinson's disease and the relatively straightforwardexploration of the clinical effects of this technique on other targets,researchers are now exploring new indications for the treatment. Futuredisorders that might be treated by HF-DBS include dystonia, epilepsy,obsessive compulsive disorder, cluster headaches, obesity, and evendepression.

An important requirement for a successful outcome of the HF-DBStreatment, is the accurate placement of the stimulation electrodeswithin the stimulation target area. Mislocation of the electrodes issuspected to be a main cause of unwanted side-effects including sensorymotor effects but also mood changes such as depression and even suicidalideas. Through careful surgical procedures, neurosurgeons try tominimize the risks for such unwanted side-effects. The general procedureadvocated by experts in the field is as follows. Prior to operation, theapproximate target area is localized by means of stereotactic imagingprocedures. Subsequently, an implantation trajectory is planned thatbears minimal risk for damage.

Still, these methods lack the accuracy that is needed for an immediatesuccessful positioning of the stimulation electrodes for two reasons.First, the exact functional anatomy within the target nucleus or brainregion cannot yet be captured by imaging, as it often spans just a fewmm, or even less, within the total nucleus or region. Second, positionchanges in the brain may occur when surgically opening the skull toimplant the electrodes and when inserting the electrodes. The currentbest practice, therefore, is to perform prior to implantation of chronicstimulation electrodes an electrophysiological exploration of the targetarea with test electrodes that are implanted along several paralleltrajectories towards the target area, capturing a sufficiently largescan volume to guarantee that the optimal stimulation target area islocated in the sampled volume of tissue. Micro-recordings of the neuralfiring patterns are performed to explore the detailed functionalboundaries of the various anatomic structures. Test stimulation isperformed to assess the efficacy of the stimulation at various candidatelocations. Only after the micro-recordings and test-stimulation haveuncovered the precise location of the stimulation target area, thechronic stimulation electrodes are implanted.

Although indispensable for successful surgery, the electrophysiologicalexploration of the HF-DBS target area brings with it severedisadvantages. First, the operation time is extended by several hoursleading to increased burden for the patient (who is awake duringsurgery) as well as heightened costs of the procedure. Second, themultiple implantation trajectories of the test electrodes and thesubsequent final implantation of the chronic electrodes raises the risksof hitting a blood vessel leading to hemorrhage.

Therefore, there is a need for an improved DBS lead system and methodthat allows a first time, direct and accurate placement by implantationof the stimulation electrodes within the stimulation target area, whichthe herein disclosed methodology and system satisfies.

According to the present disclosure, a deep brain stimulation (DBS) leadand method for providing therapeutic electrical stimulation to tissue ina stimulation target area of a patient's brain is disclosed, which iscapable of facilitating the location of the target area and thedetermination for each of the stimulation elements of the requiredstimulation parameters needed to provide the therapeutic stimulation tothe brain tissue in the stimulation target area, without requiring anyadditional implantations of the lead after the first implantation.

Specifically, it is an object of this invention to provide a deep brainstimulation lead having a distal end for providing therapeuticelectrical stimulation to tissue in a stimulation target area of apatient's brain, comprising:

an array of one or more stimulation elements and one or more sensingelements located at the distal end of the lead;

each of the one or more stimulation elements is capable of providingelectrical stimulation to the brain tissue in the target area; and

each of the one or more sensing elements is capable of detectingelectrical signals produced by nerve cells within the brain;

wherein after the first implantation of the lead into the brain along atrajectory that is pre-determined by non-surgical procedures, the arrayof stimulation and sensing elements is capable of facilitating thelocation of the target area and the determination for each of thestimulation elements of the required stimulation parameters needed toprovide the therapeutic stimulation to the brain tissue in thestimulation target area, without requiring any additional implantationsof the lead after the first implantation.

Another object is to provide a stimulation lead wherein the stimulationelements are metal electrodes.

Another object is to provide a stimulation lead wherein the sensingelements are metal micro-electrodes or capacitative sensing elements.

Another object is to provide a stimulation lead wherein the one or morestimulation elements and the one or more sensing elements aredistributed in an array circumferentially on the surface of the lead inthe proximity of the distal end of the lead.

Another object is to provide a stimulation lead wherein the sensingelements are each individually capable of detecting one or more ofelectrical signals, action potentials, field potentials, biochemicalsignals and neurotransmitters.

Another object is to provide a stimulation lead wherein the area of asingle sensing element is smaller than the area of a single stimulationelement.

Another object is to provide a stimulation lead wherein a plurality ofsensing elements are electrically combined to detect a single electricalsignal.

Another object is to provide a stimulation lead wherein the number ofsensing elements is larger than the number of stimulation elements.

Another object is to provide a stimulation lead wherein the stimulationparameters are selected from one or more of stimulation amplitude,polarity, duration repetition frequency, waveform, and relative phasewithin the stimulation duty cycle.

Another object is to provide a stimulation lead wherein the lead furthercomprises a controller for receiving signals from the one or moresensing elements, for determining the location of the target area andfor determining which of the stimulation elements is located in or nearthe target area and that should be selected to provide the therapeuticstimulation to the brain tissue in the target area.

Another object is to provide a stimulation lead wherein the controlleris capable of determining for each of the selected stimulation elementsthe required stimulation parameters needed to provide the therapeuticstimulation to the brain tissue in the target area.

Another object is to provide a stimulation lead wherein the controlleris capable of using the signals received from one or more specificsensing elements to control relative stimulation amplitudes and/ortimings of one or more specific stimulating elements.

Another object is to provide a stimulation system for providing afterimplantation therapeutic electrical stimulation to tissue in astimulation target area of a patient's brain, comprising:

a pulse generator for generating and transmitting electrical pulsesrequired for the stimulation; and

a deep brain stimulation lead having a distal end for providing afterimplantation therapeutic electrical stimulation to tissue in astimulation target area of a patient's brain, comprising:

an array of one or more stimulation elements and one or more sensingelements located at the distal end of the lead;

each of the one or more stimulation elements is capable of providingelectrical stimulation to the brain tissue in the target area; and

each of the one or more sensing elements is capable of detectingelectrical signals produced by nerve cells within the brain;

wherein after the first implantation of the lead into the brain along atrajectory that is pre-determined by non-surgical procedures, the arrayof stimulation and sensing elements is capable of facilitating thelocation of the target area, the association and/or selection ofstimulation elements in or near the target area, and the determinationfor each of the selected stimulation elements of the requiredstimulation parameters needed to provide the therapeutic stimulation tothe brain tissue in the stimulation target area, without requiring anyadditional implantations of the lead after the first implantation.

Another object is to provide a method of providing therapeutic deepbrain electrical stimulation to tissue in a stimulation target area of apatient's brain, comprising:

determining by non-surgical imaging procedures the approximate targetarea for stimulation and the trajectory for implantation of a deep brainstimulation lead into the approximate target area;

implanting along the trajectory and into the approximate target area thedeep brain stimulation lead, the stimulation lead comprising:

an array of one or more stimulation elements and one or more sensingelements located at the distal end of the lead;

each of the one or more stimulation elements is capable of providingelectrical stimulation to the brain tissue in the target area; and

each of the one or more sensing elements is capable of detectingelectrical signals produced by nerve cells within the brain; whereinafter the first implantation of the lead into the brain along atrajectory that is pre-determined by non-surgical procedures, the arrayof stimulation and sensing elements is capable of facilitating thelocation of the target area, the association and/or selection ofstimulation elements in or near the target area, and the determinationfor each of the selected stimulation elements of the requiredstimulation parameters needed to provide the therapeutic stimulation tothe brain tissue in the stimulation target area, without requiring anyadditional implantations of the lead after the first implantation;

detecting by the one or more sensing elements of the electrical signalsproduced by nerve cells within the brain;

determining from the detected electrical signals produced by nerve cellswithin the brain the three dimensional spatial location and boundary ofthe stimulation target area within the approximate target area;

determining which of the one or more specific stimulation elements willbe selected to provide stimulation to the brain tissue within thestimulation target area and the specific stimulation parameters for eachof the one or more selected stimulation elements to be used during thestimulation; and

performing stimulation of the tissue within the stimulation target areaof the brain with the selected stimulation elements using the specificstimulation parameters for each of the selected stimulation elements.

Another object is to provide a method wherein the detecting by the oneor more sensing elements of the electrical signals produced by nervecells within the brain, further comprises:

reading out the electrical signal characteristics of the nerve cellswithin the brain detected by the one or more sensing elements; and

determining the specific sensing elements that detect the signalcharacteristics that correspond to the stimulation target area.

Another object is to provide a method further comprising prior to thestep of performing the stimulation of the brain tissue:

testing the stimulation target area by delivering test electricalstimulation by the selected one or more stimulation elements to thebrain tissue in the stimulation target area and repeating the steps ofthe method as needed until confirmation of a functionally efficientstimulation target area is obtained.

Another object is to provide a method wherein the stimulation parametersare selected from one or more of stimulation amplitude, polarity,duration repetition frequency, waveform, and relative phase within thestimulation duty cycle.

These and other aspects of the invention are explained in more detailwith reference to the following embodiments and with reference to thefigures.

FIG. 1 depicts a schematic coronal section through the brain showinganatomical locations of structures involved in basal ganglia pathways.Targets for HF-DBS in the treatment of Parkinson's disease are thesubthalamic nuclei and the globus pallidus internal segments.

FIG. 2 depicts a schematic layout of a state-of-the-art DBS systemconsisting of an implanted lead carrying circumferential stimulationelectrodes and connected by means of an extension wire to an implantedpulse generator.

FIG. 3 shows an embodiment of a DBS lead with array of stimulationelements (circles) and sensing elements (triangles).

FIG. 4 shows an embodiment of a 3D distribution of stimulation elements(squares) and sensing elements (circles).

FIG. 5 shows the determination of a stimulation target area based oncharacteristic signal patterns of brain nerve cells.

FIG. 6 shows an example of monopolar synchronous stimulation on selectedstimulation elements 1-6.

FIG. 7 shows an example of synchronous stimulation with amplitude- andpolarity-mediated stimulation field steering on selected stimulationelements 1-6.

FIG. 8 shows an example of complex stimulation patterns on selectedstimulation elements 1-6.

High frequency deep brain stimulation (DBS), such as of the thalamus orbasal ganglia, is used for the treatment of movement disorders such asEssential Tremors or Parkinson's Disease. FIG. 1 shows a schematicdrawing depicting the coronal section of the brain, including anatomicallocations of structures involved in basal ganglia pathways.

A typical electrical brain stimulation system comprises a pulsegenerator operatively connected to the brain by a lead. The lead has oneor more stimulating electrodes at its distal end and is designed to beimplanted within the patient's brain so that the system of electrodes isoptimally and safely positioned for the desired stimulation of braintissue at a stimulation target area site. FIG. 2 shows a schematiclayout of a state-of-the-art DBS system including implanted stimulationlead having stimulation electrodes or elements, and implanted pulsegenerator connected thereto.

In a typical DBS procedure the initial step towards effective brainstimulation involves localization or mapping of functional brainstructures. Especially when the target is new, in the sense that thereis little or no statistical data to identify the target locationreliably, it is necessary to determine where within the boundary of thefunctional target area effective and safe stimulation may be delivered.

Therapeutic benefit and non-desired effects of brain lesioning andchronic neuromodulation depend critically on this localizationprocedure. This procedure involves three primary steps. First,anatomical localization of brain targets is accomplished usinganatomical brain atlases, imaging by means of positive contrast x-rays,CT or MRI under stereotactic conditions. Such standard well knownimaging techniques are used to make an initial determination of locationcoordinates for the target to which the lead will be directed.

Second, electrophysiological identification of functional boundariesbetween brain structures is carried out by means of single- ormulti-cell or multi-recording of characteristic cell discharge patterns.Such a procedure may also be referred to as micro recording orsemi-micro recording. Micro recording and semi-micro recording requireuse of an electrode that is small enough to differentiate between singlecell activity or multi-cellular activity, and thus requires amicro-electrode with a very small surface area, e.g. between 1-1000square micrometers for a semi-micro-electrode and less than one squaremicrometer for a micro-electrode.

The third step involves electrical test stimulation within thefunctional brain structures that have been located. Test stimulation ofthe selected brain structure is necessary to determine: (1) efficacy ofstimulation in the identified functional brain structure, and (2) anyside effects caused by stimulation of the brain in this area. If thestimulation electrode is too close to the boundary of the identifiedbrain structure the function of adjacent brain structures may bemodulated, which in turn can lead to undesired side effects. Teststimulation is clinically most relevant when performed with an electrodeor electrodes having a surface area equivalent to that of the chronicimplantable electrodes, e.g., in the range of about 1-20 squaremillimeters.

Currently, after the first step of determining a target location, a leadcontaining a micro-electrode is placed in the brain to identifyfunctional boundaries with single-cell recording. Then the leadcontaining the micro-electrode is withdrawn from the brain tissue. Afterthis step, a further step of withdrawing the micro-lead and replacing itwith a macro-lead or a third chronic brain stimulation lead may alsooccur. Those replacements typically require multiple insertions of theleads, all most preferably along the same trajectory path, and thereforeincrease the risk of intra-cranial hemorrhages with severe permanentdisability as a potential consequence. Furthermore, once a lead ispositioned and tested to determine that results of stimulation aresatisfactory, it is critical that the lead remain in the same place,because even one millimeter of electrode displacement in the wrongdirection may cause unsatisfactory results or injury to the brain.Removal of the micro-lead and replacement with one or more other leadsalso increases the risk that the lead is no longer located in or closeenough to the functional target identified by micro recording. Thus itwould be desirable to create a lead and a method that is capable ofrequiring only one implantation of the lead into the patient's brain andfacilitates the determination of the stimulation target area andspecific stimulation elements and stimulation parameters to enabletherapeutic electrical stimulation of the brain tissue.

This is accomplished with the stimulation lead, system and method ofproviding DBS stimulation using the lead according to the inventiondisclosed herein. The stimulation lead according to the inventionincludes an array of one or more stimulation elements and one or moresensing elements located at the distal end of the lead; each of the oneor more stimulation elements is capable of providing electricalstimulation to the brain tissue in the target area; and each of the oneor more sensing elements is capable of detecting electrical signalsproduced by nerve cells within the brain. After the first implantationof the lead into the brain along a trajectory that is pre-determined bynon-surgical procedures, the array of stimulation and sensing elementsis capable of facilitating the location of the target area and thedetermination for each of the stimulation elements of the requiredstimulation parameters needed to provide the therapeutic stimulation tothe brain tissue in the stimulation target area, without requiring anyadditional implantations of the lead after the first implantation.

The stimulation lead comprises an array of one or more sensing elementsand one or more stimulation elements located at the distal or advancingend of the lead during implantation into the brain of a patient, andwhich will ultimately be in close proximity to the brain tissue to betherapeutically electrically stimulated in the stimulation target area.The array of sensing and stimulations elements can take many geometricalpatterns, can be in a three-dimensional distribution about the lead andcan be realized by using more than a single lead carrying at least oneof the sensing and/or stimulation elements. For example, FIG. 3 shows anembodiment of a DBS lead with an array of stimulation elements (circles)and sensing elements (triangles). FIG. 4 shows an embodiment of 3Ddistribution of stimulation elements (squares) and sensing elements(circles).

The stimulation elements, in one embodiment of the invention, are metalelectrodes. In another embodiment the stimulation elements can be, forexample, distributed circumferentially along the lead; for example, inan array along the circumference of the lead.

The sensing elements can also, for example, be distributedcircumferentially along the lead; for example, in an array along thecircumference of the lead. The sensing elements can be, for example,metal micro-electrodes or capacitative sensing elements. The sensingelements are each independently capable of detecting one or more ofelectrical signals, action potentials, field potentials, (bio)chemicalsignals and neurotransmitters. In an embodiment several sensing elementsare electrically combined to detect a single electrical signal. Inanother embodiment the area of a single sensing element is smaller thanthe area of a single stimulation element.

The detected information provided by the sensing elements, such as theelectric signals or other signals above-mentioned produced by the brainnerve cells, is utilized by a controller or processing unit incommunication with the sensing and stimulating elements to facilitatethe spatial location and boundary of the stimulation target area in thebrain, as is shown in FIG. 5. Also, such detected informationfacilitates the determination of which specific stimulating elementswill be used in providing therapeutical electrical stimulation to thebrain tissue in the stimulation target area, as well as the stimulationparameters that will be used for each stimulation element. Suchstimulation parameters include, for example, one or more of stimulationamplitude, polarity, duration repetition frequency, waveform, andrelative phase within the stimulation duty cycle. FIGS. 6-8 show, forexample, several possible stimulation patterns for stimulation elementsidentified as numbers 1-6.

The controller or processing unit can be utilized for one or morefunctions, such as, for processing signal data, receiving signal data,transmitting signal data or new commands; communicating with atechnician or physician or other component of the lead system, such asone or more of the sensing and/or stimulating elements, externalprocessors, computers, viewing monitors, etc. Thus, for example, thecontroller may be integrated in the probe or DBS unit. Alternatively,the controller may be located externally to the DBS lead or system, forexample at a workstation, to carry out the extensive computations neededfor practicing the method of DBS stimulation, including stimulationtarget area determination. Also, the brain signals obtained by the oneor more sensing elements may, for example, be presented in viewableform, for example graphically, to a user (for example, a physician) toenable the user, possibly with the help of computer-analysis/processingof the signal/data to make initial suggestions for the optimumstimulation target area and placement of the DBS lead for stimulation.This latter approach most closely corresponds to current best practice;namely, the neurophysiologist determines the target position for the DBSlead based on sensed signals.

In an embodiment the stimulation elements are directly associated withthe sensing elements. The association is based on a geometric relationbetween the position of the sensing and stimulation elements. Forexample, each stimulation element may be associated with a singlesensing element or combination of sensing elements; or each stimulationelement can be associated with another unique sensing element, forexample, a sensing element for detecting one type of electric signal; orthe number of sensing elements is larger than the number of stimulationelements. When the number of sensing elements is greater than the numberof stimulating elements, a “center of gravity” approach may be used toassociate the sensing and stimulating elements; for example, if multiplesensing elements surrounding a stimulation element pick up the correctsignals, this stimulation element may be presumed to lie in the targetarea for stimulation. The sensing elements may, for example, pick upfiring patterns of neurons and use the characteristics of these signalsto discriminate between different brain regions. Alternatively, thesensing elements may also measure local impedance to discriminatebetween gray and white matter and thus obtain additional informationabout local neuro-anatomy in the surrounding of the probe. By combiningmultiple measurement types the discrimination between different tissuetypes, anatomical/functional structures, etc., will become moreaccurate. In another embodiment field steering techniques are employedto finely position the target stimulation area or field. In anotherembodiment relative stimulation amplitudes and/or timings of stimulatingelements are associated with sensing elements. Also, the detected signalinformation by the sensing elements can be read out in parallel orsequentially.

The stimulation lead can be incorporated into a stimulation system forproviding after implantation therapeutic electrical stimulation in astimulation target area of the brain of a patient. Such a systemincludes a pulse generator for generating and transmitting electricalpulses required for stimulation to the stimulating elements.

In another embodiment of the invention, a method of providingtherapeutic deep brain electrical stimulation to tissue in a stimulationtarget area of a patient's brain is disclosed comprising determining bynon-surgical imaging procedures the approximate target area forstimulation and the trajectory for implantation of a deep brainstimulation lead into the approximate target area; implanting along thetrajectory and into the approximate target area the deep brainstimulation lead, the above disclosed stimulation lead; detecting by theone or more sensing elements of the electrical signals produced by nervecells within the brain; determining from the detected electrical signalsproduced by nerve cells within the brain the three dimensional spatiallocation and boundary of the stimulation target area within theapproximate target area; determining which of the one or more specificstimulation elements will be used to provide stimulation to the braintissue within the stimulation target area and the specific stimulationparameters for each of the one or more stimulation elements to be usedduring the stimulation; and performing stimulation of the tissue withinthe stimulation target area of the brain with the specific stimulationelements using the specific stimulation parameters for each of thespecific stimulation elements.

Another embodiment provides that the detecting by the one or moresensing elements of the electrical signals produced by nerve cellswithin the brain, further comprises reading out the electrical signalcharacteristics of the nerve cells within the brain detected by the oneor more sensing elements; and determining the specific sensing elementsthat detect the signal characteristics that correspond to thestimulation target area.

Another embodiment provides a method further comprising prior to thestep of performing the stimulation of the brain tissue, testing thestimulation target area by delivering test electrical stimulation by thespecific one or more stimulation elements to the brain tissue in thestimulation target area and repeating the steps of the method as neededuntil confirmation of a functionally efficient stimulation target areais obtained.

In another embodiment, there is provided a method for“first-time-right-placement” of a DBS lead. This is achieved by usingthe stimulation lead according to the invention carrying an array ofstimulation elements and an integrated array of sensing elements. Themethod consists of the following steps:

1. implanting the novel DBS lead along the trajectory as determined bystereotactic imaging procedures (and/or other surgery planning tool)well within the approximate target area of the brain where thestimulation target area for the tissue to be stimulated should belocated.

2. reading out the signal characteristics detected by the varioussensing elements integrated in the DBS lead.

3. determining the sensing elements that detect the signalcharacteristics corresponding to the intended stimulation target area.

4. associating with the sensing elements that detect the signalcharacteristics corresponding to the intended stimulation target areathe spatial location and boundary extent of the stimulation target area.

5. associating with the derived spatial location of the stimulationtarget a shape of the required stimulation field needed to cover thestimulation target area.

6. associating with the required stimulation field a group of specificstimulation elements.

7. optionally testing the so identified intended stimulation target areaby delivering test stimulation using the group of specific stimulationelements, and optionally repeating steps 2 to 7 until confirmation of afunctionally efficient stimulation target area is obtained;

a. further optionally using available additional diagnostic tools tosupport targeting, e.g. intra-operative functional imaging, fusedimaging, etc.

8. determining for each of the specific stimulation elements therequired stimulation parameters like stimulation amplitude, polarity,duration, repetition frequency, waveform, and relative phase within thestimulation duty cycle.

9. performing stimulation on the brain tissue in the stimulation targetarea with the associated specific stimulation elements according to thederived stimulation parameters.

While the present invention has been described with respect to specificembodiments thereof, it will be recognized by those of ordinary skill inthe art that many modifications, enhancements, and/or changes can beachieved without departing from the spirit and scope of the invention.Therefore, it is manifestly intended that the invention be limited onlyby the scope of the claims and equivalents thereof.

The invention claimed is:
 1. A stimulation lead having a distal end forproviding therapeutic electrical stimulation to tissue in a target area,the lead comprising: an array of a plurality of stimulation elements anda plurality of sensing elements located at the distal end of the lead,the array including columns of two or more of the plurality ofstimulation elements, the columns extending down a longitudinal lengthof the stimulation lead and spaced from one another around thecircumference of the stimulation lead, at least one of the plurality ofstimulation elements being adjacent to and surrounded by two or more ofthe plurality of sensing elements, each of the plurality of sensingelements configured to detect electrical signals, at least one of theplurality of sensing elements being positioned between two or more ofthe plurality of stimulation elements, a number of the plurality ofsensing elements being greater than a number of the plurality ofstimulation elements, the plurality of sensing elements comprising aplurality of sets of sensing elements, each of the sets of sensingelements comprising two or more sensing elements, each of the pluralityof stimulation elements being directly associated with one of the setsof sensing elements, the association being based on a geometric relationbetween which sets of sensing elements surround which ones of theplurality of stimulation elements, and each set of sensing elements isassociated with only one stimulation element that is surrounded byrespective set of sensing elements; and a controller configured toreceive signals from one or more of the plurality of sensing elements,derive a spatial location and boundary of the target area based onlocations of the sensing elements that sensed the signal, and determinethat one or more of the plurality of stimulation elements that aresurrounded by the respective sets of the sensing elements whose sensingelements sensed the signal lie in the target area and should provide thetherapeutic electrical stimulation that covers the spatial location andthe boundary of the target area, and control delivery of the therapeuticelectrical stimulation via the determined stimulation elements.
 2. Thestimulation lead of claim 1, wherein the plurality of stimulationelements are metal electrodes.
 3. The stimulation lead of claim 1,wherein the plurality of sensing elements are metal microelectrodes orcapacitive sensing elements.
 4. The stimulation lead of claim 1, whereinthe plurality of stimulation elements and the plurality of sensingelements are distributed in an array circumferentially on the surface ofthe lead.
 5. The stimulation lead of claim 1, wherein the plurality ofsensing elements are each individually capable of detecting one or moreof electrical signals, action potentials, field potentials, biochemicalsignals and neurotransmitters.
 6. The stimulation lead of claim 1,wherein the area of one of the plurality of sensing elements is smallerthan the area of two of the plurality of stimulation elements.
 7. Thestimulation lead of claim 1, wherein the plurality of sensing elementsare electrically combined to detect a single electrical signal.
 8. Thestimulation lead of claim 1, wherein the stimulation parameters areselected from one or more of stimulation amplitude, polarity, durationrepetition frequency, waveform, and relative phase within thestimulation duty cycle.
 9. The stimulation lead of claim 1, wherein thecontroller is configured to determine required stimulation parametersneeded for the therapeutic electrical stimulation for each of theplurality of stimulation elements associated with the sensing elementsthat sensed the signal.
 10. The stimulation lead of claim 1, wherein thecontroller is configured to use the signals received from one or more ofthe plurality of sensing elements to control relative stimulationamplitudes and/or timings of each of the plurality of stimulationelements associated with the sets of sensing elements that sensed thesignal.
 11. The stimulation lead of claim 1, wherein a set of thesensing elements comprises six sensing elements adjacent to and spacedaround only one of the plurality of stimulation elements with which theset of sensing elements is associated.
 12. The stimulation lead of claim1, wherein the at least one of the plurality of sensing elements ispositioned between three of the plurality of stimulation elements.